This has little if anything to do with being in a city, and more to do with how expensive a person's tastes are.
Making fun for oneself is easy if need are simple. I enjoy a walk with another human because I'd rather do that than go to a shitty steakhouse. I'll make art on a Saturday afternoon, or cook. There's always free events of all kinds just check the local promotion groups. Lots of local socializing and board game groups. Bird watching. Bike rides are effectively free, so is going for a picnic in an area you haven't been to.
Grab a ball and go to the park. Get some unsalted sunflower seeds at the dollar store and feed the chickadees. Hit the local Ultimate pick-up game. Go to a bar and *gasp* don't drink and just enjoy the live music. Hell if $20 is in the inventory, go to the pinball arcade for 2 hours.
You can have fun for $10K and you can have fun for $0, it's up to you.